Efficacy and safety of radiotherapy in acromegaly

Abstract

Background and aims: Transsphenoidal surgery remains the treatment of choice in acromegaly, yet 40-50% of patients require secondary forms of therapy such as radiation therapy (RT) and somatostatin analogues (SA). We undertook this study to evaluate the efficacy and safety of RT in acromegaly.

Methods: Forty patients with acromegaly treated with RT (mean dose, 52 Gy) after failed pituitary surgery between 1993 and 2007 were analyzed; all were clinically and biochemically active. Patients were evaluated with yearly hormonal measurements [basal and glucose-suppressed growth hormone (GH), IGF-1, thyroid-stimulating hormone (TSH), free T4, cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone or estradiol and prolactin (PRL)] and with magnetic resonance imaging every 2 years.

Results: Mean age of patients was 52.9 ± 12.1 years and 85% were female. All subjects had been followed for 1 year, 75% for 3 years, 70% for 5 years and 35% for 10 years. The median basal GH level fell from a baseline of 8.8 ng/mL to 2.27 ng/mL at 5 years (p = 0.001) and to 1.88 ng/mL at 10 years (p = 0.001). A GH <1 ng/mL was achieved by 46% and 57% of the patients at 5 and 10 years of follow-up, respectively. The proportion of patients achieving a normal IGF-1 was 36% at 5 years and 43% at 10 years. Before RT, hypothyroidism, hypocortisolism and hypogonadism were present in 44%, 26% and 74% of patients, respectively. After 5 years of follow-up (n = 28), these figures increased to 51%, 41% and 79% and over a third of the group had panhypopituitarism. One patient developed optic neuritis and another patient was diagnosed with a meningioma 10 years after RT. No cerebrovascular events or deaths occurred.

Conclusions: RT is an effective, low-cost and reasonably safe means of controlling acromegalic activity, particularly useful in parts of the world where SA are not readily available.